1. Field of the Invention
The present invention relates to a plug detecting device, especially to a plug detecting device installed on electronic products for detecting if a plug is plugged into a connector.
2. Description of the Prior Art
The plug detecting function is used for detecting if a plug of an electronic product is plugged into a connector. According to demand, some electronic products have to detect if the plug is plugged into the connector, so as to shunt the signals or remind the user that the plug is not plugged in yet.
According to the differences in standard or design, the connector comprises a plurality of pin holders with some functions, and the plug comprises the same number of pins with the same functions corresponding to the pin holders. The plug detecting method of the electronic products of the prior art is to detect the potential of one specific pin holders at fixed periods of time. Once the plug is plugged into the connector, the potential of the specific pin holder will change. The electronic product perceives the plug has been plugged into the connector and performs the corresponding function.
The plug detecting function of the prior art has to utilize a specific pin holder of a connector and the corresponding pin of a plug to perform detection. However, due to differences in standard and design, connectors of many standards may not provide the specific pin holder to perform detection. When each the pin holder has the specific function for transmitting signals respectively, there will be no extra pin holder to detect the plug. Therefore, the prior art cannot achieve the objective of detecting the plug via the present hardware.
Referring to FIG. 1, FIG. 1 is an external view of the plug 10 of the prior art. The standard of the plug 10 is S-Video (4-pole miniDIM), i.e. S-terminal, which is usually used to transmit signals between video/audio player and image output/input apparatus, e.g. communication of signals between DVD player or Digital Video Disc Player and TV. The plug 10 comprises four pins 11, 12, 13, 14, and each pin of the plug 10 is corresponding to a pin holder on the connector respectively. Moreover, the plug 10 comprises a metal outer ring 15. In this example, according to the standard of the plug 10, each pin and each the corresponding pin holder have different functions of signal communication respectively. Pin 11 is used for luminance return; pin 12 is used for chrominance return; pin 13 is used for luminance, and pin 14 is used for chrominance. The standard of the connector and the plug does not provide the needed pin holder and the corresponding pin for detecting the plug. If a designer wants to add the plug detecting function, he/she can only reset the signal communication protocol of the connector without increasing the number of pin holders, so as to obtain a pin holder for detecting the plug; otherwise, the designer can readjust the circuit of the connector and the plug to add a new pin holder and a corresponding pin for detecting the plug. The above-mentioned methods need to modify the communication manner, readjust the circuit, alter the hardware, or so on, so the cost of production is high, and the design is inconvenient.